1. Field of the Invention
This invention pertains generally to underground fluid and water storage and detention systems, and more particularly, to structural support beams placed inside an underground chamber.
2. Description of the Related Art
Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Water storage and detention is essential for any number of varied applications. Water shortages due to drought, excess demand or limited water delivery infrastructure are common and water storage is, in many areas, or under certain conditions, necessary or desirable for people's health, safety and well-being. Storm water detention and control is necessary to preserve public and private property and to comply with regulations of local and state governments, which regulations are becoming increasingly common and more broadly applied. There are also many commercial applications for water storage and control systems. Water storage systems are desired by homeowners seeking to have water available for irrigation, household use, fire suppression or to supplement water available from wells or water utilities. Commercial and industrial water users store water for use in irrigation, cooling, cleaning, washing and manufacturing processes. Water is stored on farms for use with crops and livestock and at hospitals for emergency use. Storm water is stored or detained temporarily to capture large water volumes and thus reduce pressure on flood control systems during storm events or to prevent excessive run-off and reduce pollution flowing into streams, rivers or the sea.
Common systems for storing water, collected from roofs and ground surfaces, include containers, barrels or tanks sitting above ground for relatively small quantities of stored water and, for those desiring to store large or mass quantities of water, large above ground tanks or a series of large tanks. These systems all suffer the disadvantages of occupying above ground or surface area on property that could be put to other use; they are unsightly and the quality of the water stored above ground is generally lower than that of water stored below ground. Water stored below ground is less subject to evaporation loss and can be stored longer with less contamination risk than can occur in stagnant water stored above ground.
One common type of water storage system below ground includes a variety of tanks or cisterns that are buried under the surface and do not present an unsightly view and allow for use of the surface area; in some cases the surface area can be heavily loaded by such uses as parking lots and roads. The disadvantages of these systems are that they are costly, disruptive to the site and expensive to install, and they require ballast to prevent them from rising up from the ground. The ballast is often in the form of heavy weights, made of concrete or other heavy materials, that hold down the tank or cistern, or, alternatively, in the form of the weight of a substantial quantity of water retained in the tank or cistern at all times. Retaining a substantial quantity of water in the tank or cistern has the major disadvantage of reducing its usable storage capacity.
Another type of below ground water storage system is a modular system that consists of a number of parts that constitute a support structure sitting inside an excavated chamber. The chamber is lined with an impermeable liner of plastic or rubber material if the chamber is used for water storage. Alternatively, the chamber is lined with permeable filter materials in the case of water detention uses that allow water to pass through and eventually percolate the detained water into the soil. The support structure of the chamber is designed to prevent the surrounding soil from collapsing into the void space of the chamber and thus maintain the chamber void space for water storage or detention. In some cases, the support structure also provides a heavier surface load bearing capability so the ground surface can be used for parking lots and roads. Modular support structures include vertical pipes, columns, boxes or panels set vertically on edge to support the surface loads and prevent the collapse of the chamber void space.